IOS get notified when UI updates.

Question

I have a custom keyboard extension. This function is called when the delete key is pressed:

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0),
            {
                for _ in 1..<50
                {
                    (self.textDocumentProxy as UIKeyInput).deleteBackward()
                }
                print("Deletion End")
                self.deleteCounter = 0
        })

I do not think the dispatch_async is relevent but I included it, just incase.

The problem is that even though my console prints "Deletion End" once the loop is finished, the UI of the textfield does not update until a second or two has passed.

It seems calling

(self.textDocumentProxy as UIKeyInput).deleteBackward()

Does not immediately delete a character and update the UI.

How can I be notified when the UI is actually updated?

if my answer fixes your problem please mark it as right, thanks. — Marco Santarossa, Sep 02 '16 at 20:15

score 0 · Answer 1 · answered Sep 02 '16 at 17:27

0

Change like this:

dispatch_async(dispatch_get_main_queue(),{
                for _ in 1..<50
                {
                    (self.textDocumentProxy as UIKeyInput).deleteBackward()
                }
                print("Deletion End")
                self.deleteCounter = 0
        })

Explanation:

The UI must work in the Main thread so when you work with the background queue you always have to dispatch in main queue the UI updates.

answered Sep 02 '16 at 17:27

Marco Santarossa

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This does not seem to work. The console still prints "Deletion End" before the UI actually changes. – Foobar Sep 02 '16 at 23:10

IOS get notified when UI updates.

1 Answers1